As exposure apparatuses for exposing a resist, there are a light exposure apparatus and an electron beam exposure apparatus. Among these, the electron beam exposure apparatus is suitable for small-quantity production such as that for engineering samples. This is because, unlike the light exposure apparatus, the electron beam exposure apparatus uses no reticle, and therefore may save the time and cost to manufacture the reticle.
In an exposure step of the electron beam exposure apparatus, a semiconductor substrate and the electron beam exposure apparatus are aligned by using an alignment mark provided in the semiconductor substrate to prevent misalignment between the semiconductor substrate and the electron beam exposure apparatus.
Various types of alignment mark structures are proposed. By use of any of the structures, an electron beam is scanned over the semiconductor substrate and the intensity of reflected electrons from the alignment mark is checked. Since the intensity of reflected electrons varies between the alignment mark and other regions, it may be possible to identify the position of the alignment mark by monitoring the intensity of reflected electrons and to perform alignment between the semiconductor substrate and the electron beam exposure apparatus.
It is preferable to improve accuracy of the alignment to satisfactorily exploit a high resolution performance of the electron beam exposure.    [Patent Document 1] Japanese Laid-open Patent Publication No. 11-054607    [Patent Document 2] Japanese Laid-open Patent Publication No. 58-213425    [Patent Document 3] Japanese Laid-open Patent Publication No. 60-111424    [Patent Document 4] Japanese Laid-open Patent Publication No. 06-132202    [Patent Document 5] Japanese Laid-open Patent Publication No. 2005-340321    [Patent Document 6] Japanese Laid-open Patent Publication No. 56-094741